The present invention relates to sheet-like administration forms for application as cosmetic, pharmaceutical or food-technological products.
Flat-shaped administration forms for use in the oral region and on the mucous membranes of the mouth are well-known. Thus, U.S. Pat. No. 3,444,858 (Russell, 1969) already describes medicament strips based on a gelatine-like material.
In EP 0 216 762 a water-soluble film of starch, gelatine, glycerine or sorbite is disclosed which is coated employing a roll-coating method. The document shortly mentions in this context that such dosage forms can also be produced for chemical reagents, flavours and the like.
A formulation that is in principal suitable for making sheet-like systems is disclosed in EP 0 460 588. Here, the composition of 20 to 60 percent by weight of film former, 2 to 40% gelatinizing agent, 0.1 t 35 percent by weight of active substance (here: flavouring agent) and a maximum of 40 percent by weight of an inert filler is regarded as affording particular advantages. DE 36 30 603 sees particular advantages in designing the flat-shaped dosage form on a carrier material (release film) so as to peelable in doses.
U.S. Pat. Nos. 4,128,445 and 4,197,289 (Sturzenegger, 1978) address possible technical solutions in connection with the loading with active substances.
For drug-containing sheet-like systems a two-layer structure of a water-swellable layer and a water-insoluble barrier film is also regarded as advantageous (U.S. Pat. No. 5,047,244).
In the manufacture of such films, some hydrophile film formers, especially pullulan and other glucans, but also cellulose derivatives, exhibit insufficient wetting on common coating media. This may result in premature or difficult substrate detachment as well as a resultant uneven film thickness. As a remedy, U.S. Pat. No. 4,562,020 recommends the use of a substrate circulating in the process as a loop, said substrate being based on nonpolar heat-stable polymers and, during the process, being continuously subjected to a superficial corona treatment, thus being constantly provided with a new polar surface that has a sufficiently safe wetting capability. The drying temperatures are between 40 and 110xc2x0 C.; temperatures mentioned in the Examples are 60 and 85xc2x0 C.
The aroma films produced on the pure film substrates have proved disadvantageous because of their being smooth on both sides. Such products have only limited suitability for the further processing and use in stacks formed by film cutting. Such stacks of film pieces or punched film pieces, as are frequently offered to the consumer in suitable dosage dispensers, tend to stick to each other, which makes it much more difficult to safely remove the pieces. As such film-shaped administration forms, due to their small weight per unit area (typically approx. 10 to 80 g/m2) tend to become statically charged, and since, at the same time, their surfaces, to facilitate later removal, are designed so as to be slidable on each other, this aspect is disturbing not only in use but also in the process technology.
A third demand that should be met by the process is that loss of flavour due to heat be prevented while affording maximum process rates. The prior art reveals no information pointing towards a solution to this demand.
From these requirements, which have as yet remained unsolved in the prior art, results the object of the present invention of providing processes for making sheet-like active substance carriers which enable a precise and reproducible coating quality, prevent the mutual adhesion of the finally produced pieces of film or sheet in the stack, and can be obtained, while avoiding contamination and excessive thermal load, at high production rates.
This object is achieved according to the present invention in that immediately subsequent to the coating of the solution of hydrophile polymers with added active substances and further auxiliary substances, a stream of moderately warm air (30-50xc2x0 C.) is passed over the material, whereafter the temperature is raised slightly (35-80xc2x0 C.), finally followed by a reconditioning phase at 25-50C. The process rate is advantageously regulated such that an equilibrium relative humidity of 50-75%, preferably 60-68%, is maintained in all cases. By using rough-surface substrates, preferably thermoplasts of polypropylene, polyethylene, polyethylene terephthalate, polycarbonate, and laminates of these polymers, with polyethylene-coated paper being particularly preferred, it is effectively prevented that the later-produced single film pieces stick to each other in a stack.